Arc discharge lamp filled with electron-impact excitable material carried in an inert gas



Dec. 13, 1966 H, J R L TZ 3,292,037

ARC DISCHARGE LAMP FILLED WITH ELECTRON-IMPACT EXCITABLE MATERIAL CARRIED IN AN INERT GAS Filed Dec. 30, 1964 5 Sheets-Sheet 1 55 INVENTOR HERIBERT KARL JOSEF HERGLOTZ 3, 1966 H. K. J. HERGLOTZ 3,292,037

ARC DISCHARGE LAMP FILLED WI I'H ELECTRON'IMPACT EXCITABLE MATERIAL CARRIED IN AN INERT GAS Filed Dec 30, 1964 3 Sheets-Sheet 2 INVENTOR HERIBERT KARL JOSEF HERGLOTZ ATTORNEY Dec. 13, 1966 H K J. HERGLOTZ 3,292,037

ARC DISCHARGE LAMP .F ILLED WITH ELECTRON-IMPACT EXCITABLE MATERIAL CARRIED IN AN INERT GAS Filed Dec. 50, 1964 5 Sheets-Sheet 5 INVENTOR HERIBERT KARL JOSEF HERGLOTZ ATTORNEY United States Patent 3,292,037 ARC DISCHARGE LAMP FILLED WITH ELEC- TRON-IMPACT EXCITABLE MATERIAL CAR- RIED IN AN INERT GAS Heribert Karl Josef Herglotz, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Dec. 30, 1964, Ser. No. 422,133 8 Claims. (Cl. 315-108) This invention relates generally to the field of high intensity electrical discharge lamps, and more specifically involves an improved high efiiciency, and high intensity elec trical discharge lamp combination for continuously producing radiation sufiicient in intensity and wave length to be useful commercially in conducting photochemical reactions.

It has been known that photochemical reactions of certain compounds could be accomplished by exposure to light radiation of an exciting frequency or wave length. However, it has not been possible to develop light sources of sufficient efficiency, output, controllability, and practicality to serve as suitable industrial units for accomplishing photochemical reactions on a commercial scale. For example, prior art electrical discharge lamps which can produce light radiation of an exciting frequency corresponding to the 2537 A. wave length are of the low pressure are discharge, low current density types which cannot produce radiation of suflicient intensity to be of significance commercially. Previous attempts to solve this problem by using higher pressure are discharges and by using high power inputs have not been successful but actually lowered efiiciency by undesirable broadening of the frequency range containing the exciting frequency and by undesirable overheating effects which further aggravated broadening of the critical frequency range and caused other problems. Previous attempts to utilize the lowoutput prior art lamps commercially have indicated that the number of lamps and the amount of space required would be prohibitive and entirely unsatisfactory.

Accordingly, it is one object of this invention to provide an improved high efliciency electrical discharge lamp combination which overcomes the deficiencies and disadvantages of the prior art lamps and is capable of producing high intensity radiation at the desired exciting frequency for continuous commercial photochemical processing.

It is another object of the invention to provide such an improved lamp combination which generates high intensity mercury resonance radiation in the 2537 A. wave length range and utilizes a low pressure are discharge.

It is another object of the invention to provide in this improved lamp combination means for easily and quickly assembling and disassembling the lamp and its component parts for initial fabrication, as well as for subsequent repair, maintenance, and replacement of parts.

It is a further object to provide such an improved lamp combination which is not only effective and reliable in operation but also simple and economical to manufacture and operate.

These objects are achieved by a lamp unit which generally comprises in combination, a gas-tight housing means, constructed and arranged for cooperation and operative association with a photochemical reaction vessel, said housing means comprising a first elongated tubular envelope member formed of a material pervious to light generated by said unit, said housing means further comprising a first end closure member cooperating with one end of said tubular envelope member and a second end closure member cooperating with said other end of said tubular envelope member, said unit further comprising a second inner elongated tubular member cooperating with said first tubular member to define an elongated tubular 3,292,037 Patented Dec. 13, 1966 'ice zone, preferably, said unit further comprising support means in said housing means cooperating with said second tubular member to support said second tubular member inside said first tubular member and maintain said tubular zone in a configuration having a substantially uniform predetermined thickness, said unit further comprising a first electrode assembly mounted on one of said end closure members and positioned in said housing means at one end of said zone and a second electrode assembly mounted on the other of said end closure members and positioned in said housing means at the other end of said zone, said electrode assemblies adapted to be operatively connected to an electrical power supply circuit of'predetermined characteristics, said unit further comprising a third means cooperating with one of said closure members for maintaining a predetermined low absolute pressure in said zone in said housing means, said unit further comprising a fourth means cooperating with one of said closure members for supplying a predetermined amount of an electrondmpact excitable medium, preferably a metallic vapor carried in an inert gas to said zone in said housing means, and a fifth means cooperating with said inner tubular member to maintain a predetermined temperature in said inner tubular member and said zone, said predetermined characteristics of said power supply circuit, said predetermined thickness of said zone, said predeterrnined pressure, said predetermined temperature, and said predetermined amount of medium being such that upon energization of said electrode assemblies by such power supply circuit, a high intensity light-radiating arc discharge is created and maintained in said zone between said electrode assemblies to produce sufi'icient light of a predetermined wave length range and intensity in said zone for transmission through said first tubular envelope member to space surrounding said unit such that significant photochemical efiects can be effectively produced in the surrounding space.

Other objects, features, and advantages of the invention will appear from a consideration of the following specification and claims taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a partial longitudinal cross sectional view of a simplified lamp unit embodying principles of the present invention, with certain parts broken away, and certain features shown schematically.

FIGURE 2 is a partial perspective view of the upper end portion of the lamp unit with its electrode assembly and the upper end of the inner tubular member.

FIGURE 3 is a transverse cross sectional view of the lamp unit of FIGURE 1 taken at line 33.

FIGURE 4 is a partial enlarged longitudinal cross sectional view of a lamp unit representing a preferred embodiment of the invention, showing the details of one end of the unit, especially the metallic end closure member and its easily disassembleable relationship with the other parts of the unit.

FIGURE 5 is a side elevational view of a modified lamp unit embodying features of this invention, the unit being shown as having a configuration and design for operative association and cooperation with a photochemical reaction vessel containing material to be heated by the exciting radiation of the lamp unit.

FIGURE 6 is a schematic diagrammatic presentation of a power supply circuit in combination with a lamp unit of this invention.

FIGURE 7 is a general schematic view of an overall lamp unit combination embodying principles of this invention, with certain parts shown in section for a clearer disclosure of the structural features.

Referring now to FIGURE 1, number 1 designates a low-pressure vapor discharge lamp unit according to the present invention comprising an elongated tubular or cylindrical envelope member 2, preferably of quartz joined by means of suitable graded seals with first and second glass end closure members 3 and 4, respectively, in which are arranged metallic ring electrodes 5 and 6, preferably of tungsten, sealed to outwardly extending nipples 7 and 8 of the end closure members and operatively connected to electric conducting means 9 and 10, respectively. The tubular member 2 and end closure members 3 and 4 define a fluid tight housing means. Arranged within the lamp unit and projecting concentrically thereinto through an O-ring seal S is an inner elongated tubular member 11, preferably also of quartz, which has an inlet portion 12 through which cooling water may be introduced and an outlet portion 13 for discharge of cooling water. The tubular member 11 is ...surrounded by electrode. assemblies 5 and 6, as can be seen at one end closure member in FIGURE 2. The tubular member 11 is slidably adjustable through end closure member 4. The outlet portion 13 extends upwardly into tubular member 11 to allow the circulation of cooling water therethrough. The space between the tubular members defines an annular zone 120 in which the lamp unit arc discharge occurs. This annular zone has a thickness'TH as shown in the drawings. End closure member 3 is provided with a conduit portion 14 which may-be suitably connected to a vacuum pump or other source of reduced pressure. End closure member 4 is provided with a conduit portion 15 which communicates with metal vapor pressure control means 16, adapted to maintain metal vapor pressure within desired limits, and thence to metal vapor supply means 17. A supply of an inert arc-supporting gas, preferably helium or argon, is passed to metal vapor supply means 17 via conduit 18 and valve 19. The metal-vapor-saturated inert gas leaving supply means 17 passes to discharge lamp 1 via saturation pressure control means 16 and vapor delivery line 15. Cooling finger 11 is coated with a thin layer of a low-workfunction metallic substance 130 selected from the metals iron, chromium, and aluminum, as can be more clearly seen in FIGURE 3. Illustrative lamp dimensions for the embodiment of FIGURE 1 are as follows: the overall length of lamp 1 is 13 inches, with the length of central portion 2 being 6 inches. The diameter of central portion 2 is 25 millimeters and the diameter of each of the end members is 8.5 centimeters. The annular gap 20 between the inner tubular member, or cooling finger, 11 and the internal surface of central portion 2, shown best in FIGURE 3, is approximately 1.5 millimeters. It has been discovered that, for most effective lamp operation and the avoidance of line reversal, gap 120 should be of the order of the effective mean free path of the 2537 A. light quanta [approximately 0.15 cm. as disclosed by Kenty, in the Journal of Applied Physics, 21, p. 1309- 18 (1960)], whereupon the generated 2537 A. radiation should leave the lamp without reabsorption. Conduits 14 and 15 are typically A; in. in diameter. Metal vapor pressure control means 16 comprises a 9-inch upright reflux condenser supplied with thermostatically monitored water which enters at tube 21 and leaves at tube 22. Metal vapor supply means 17 comprises a 2-inch diameter stainless steel container, the bottom surface of which is substantially covered by a quantity of mercury adapted to serve as a source of mercury vapor during operation of the lamp. Valve 19 can be a Ai-inch stainless steel Hoke needle valve. A temperature of approximately 180 C. is maintained in container 17 by electrical heating means 23. Electrode assemblies 5 and 6 are independently heated by 5 volts A.C. from the secondary coils of transformers 24 and 25, to which 110 volt 60 cycle A.C. is supplied to the primaries thereof. Lamp unit 1 can be operated on alternating current from a suitable power supply for 110 v. A.C., typically a sat-urable core reactor, which makes it possible to maintain a preset current regardless of lamp impedance.

Operation of lamp unit 1 to obtain high-intensity monochromatic output of 2537 A. radiation requires delicate balance of the variables inert gas pressure, mercury pressure, temperature of the inner tubular member or cooling finger, tungsten filament heating, current through the lamp, and voltage (not an independent variable after the other variables have been set). Operating conditions could be found such that energy of the emitted 2537 A. mercury radiation leaving the unit surface area exceeds that from a commercial high-intensity lamp (Hanovia SSA-45) by a factor of 10.

In the preferred embodiment of the lamp unit design of the present invention a demountable end closure mem ber containing the electrode assembly supporting structure and made of metal, illustrated in FIGURE 4, is used to replace the glass end closure members of FIGURE 1. Otherwise the concepts illustrated in FIGURE 1 remain basically the same. In addition to providing better mechanical support for the electrode wire, the metal end closure member is provided with a cooling chamber and convenient fittings for gas inlet and outlet tubing. Use of the metal end closure member, which can be of mild steel, prevents dimming of the lamp by evaporated tungsten, which collects on the inner metal of the closure member and thus does not deposit as an opaque coating on the light-transmitting quartz walls of the lamp. A metal end closure member at each end of the lamp also allows scaleup to a longer useful column with improved position of the inner cooling tubular member to obtain a uniform annular zone, which is necessary for uniform light emiss1on.

Referring now to FIGURE 4, end closure member 26 includes annular supporting flange 27, cylindrical body portion 28, annular superjacent flange 29, and annular capping flange 30, all of which may be made of steel. The tubular lamp envelope 2 is received within the adjoining annular openings provided by body portion 28 and support flange 27, which have been chamfered to accommodate an O-ring 31 at their juncture, for making a tight peripheral seal with the tubular lamp envelope, which is inserted until it comes to rest against the lip 32. Inner cooling tube 11 is likewise received within the adjoining annular openings provided by superjacent flange 29 and cap flange 30, which have been similarly chamfered to accommodate an O-ring seal 33. A third O-ring 34 is employed as a seal between flange portion 29 and body portion 28 in a groove provided therefor. Flanges 27 and 29 are each secured to body portion 28 with four suitable screws 35 spaced at intervals and threadingly engaging body portion 28. Capping flange 30 is similarly secured to superjacent flange 29 with four suitable screws 36 threadingly engaging flange 29. The annular openings to sealed electrode compartment 37 are flared to prevent overheating. An annular cooling chamber 38 extends upwardly from the lower face of the body portion 28 communicating with diametrically opposite water inlet 39 and outlet 40, respectively, in an upper annulus of reduced cross-section. Sealing of the cooling chamber at the interface with flange 27 is effected with annulardisc 41 welded to the chamber opening. Displaced 20 forward of the center line of taps 39 and 40 and connecting into electrode compartment 37 is a vacuum pump connection 42 which serves alternatively as a gas inlet in the opposing electrode housing. An electrically insulated port 43 is provided at 90 displaced forward of the center line of inlets 39 and 40 for insertion of a lead-in conductor 9 formed of material having a high heat conductivity and carrying heater current to a helical electrode 5 as well as current to the lamp. The other end of electrode 5 is attached to screw 44, which is threaded to the shelf of the electrode compartment, making the electrode housing the return conductor for heater current. Electrode 5 makes 2 spiral turns around cooling tube 11 and can be made of tungsten.

Typical overall dimensions for the assembled end closure member 26 are 4 inches in length by 4% inches diameter. The dimensions of the electrode compartment are typically 1% inches by 2 /2 inches in diameter. The upper annular opening receiving the cooling finger is typically A; inch in diameter. The lower annular opening receiving the lamp envelope is typically l g inches in diameter, necking down to /s inch in diameter at the entrance to the electrode compartment 37. With the end closure member construction just described, lamp dimensions are limited only by existing power supplies and a wider selection of lamp configurations can be made available for industrial use.

A lamp unit embodying this end closure member con struction and having a tubular envelope useful length (the distance between metal end closure members) of 66 centimeters and an outside diameter of 2 /2 centimeters was built enclosing an inner quartz cooling tube of 1.5 centimeters diameter, leaving an annular zone having a thickness (radial) of 4 millimeters for the positive column, taking into consideration an external tubular wall thickness of l millimeter. This lamp unit was operated from a silicon controlled rectifier power supply and a 110/600 volt 14 kva. transformer. The temperature of the inner tube was maintained at about 65 C. and the temperature of the mercury saturator at about 75 C. Argon pressure was maintained at about 2 mm. Hg. With an input power load of 1330 watts and a lamp current of 9.5 amperes the 2537 A. wave length output was 24.5 arbitrary units compared to 3.2 arbitrary units for a commercial lamp. Some sacrifice of etficiency compared to that obtained in a commercial lamp resulted, the respective values being 9-15% efficiency vs. 2030% efficiency for the commercial lamp. The metallic coating on the inner cooling tube was omitted from the experimental lamp just described. A factor of considerable importance in the performance of an earlier version of this lamp was the purity of the quartz used in the emitting envelope. Reducing the temperature of the inner cooling tube to within a range from 4565 C. decreased the light output because of precipitation of mercury; increasing the temperature above this value decreased efficiency. In FIGURE 5 is shown still another embodiment of the lamp unit of the present invention. A 60-inch U-tube configuration of quartz (area 1620 cm?) is provided with metal end closure members 26 and 26, in accordance with the showing of FIGURE 4, from which inner cooling tube elements 11 and 11, respectively, each having separate water inlet and outlet tubes 12 and 13, are positioned in the legs of the lamp, coming to rest in the axial pit-like extensions 45 and 46, which are reinforced with an excess of quartz to prevent piercing of the U-tube at these points. From the lower flange of each end closure member to the apex of the cooperating cooling-tube rest is 30 inches. The horizontal dimension between the apices of cooling tube rest extension 45 and 46 is 6 inches. No effect on tube performance from this uncooled section was noted. In all other aspects the lamp unit is the same as the hereinbefore described straight lamp unit. The metallic coating on the inner cooling tube was not used. The configuration of FIGURE 5 is particularly well adapted and constructed for cooperation with a tank-type reactor for submersion in the material to be treated.

Referring to FIGURE 6, the lamp unit of FIGURE 5 is operated from a l0O0-volt, lS-ampere current-limiting transformer 14, the primary winding 140' of which is connected to a variable autotransformer 48 energized from a 110*-volt, IOU-ampere alternating current supply at terminals 49 and 50. The secondary winding 141 of transformer 14 is connected to the lamp unit electrode assemblies. A magnetic shunt 142 having a suitable air gap therein provides the desired leakage reactance between the coi-ls 140 and 141, this reactance being used to ballast the lamp. A 400 ,uf. 0011(16115611150 may be connected across winding 48 to correct the lagging power factor effect produced by this reactance. A filament-heating transformer F comprises a primary wind- Lamp voltage 400 v. 6 kw Lamp current 15 :amp. Temperature of central tube 50 C.

Temperature of saturator 70 C.

Argon pressure 3.8 mm.

Output of 2537 A 12 arbitrary units, as compared to 1.1-1.2 units of 2537 A. for the Hanovia lamp representing an illustrative example of prior art lamps.

Therefore, by comparison with the commercially produced 280 om. Hanovia lamp (88A45) hereinbefore mentioned, which is claimed by the manufacturers to have an output of 10 w. of 2537 A., a relative analysis of applicants lamp unit can be calculated as follows.

Operation in the atmosphere:

Total output of Hanovia 88A-45 lamp 10 w. Increased-brilliance factor (energy emitted per unit surface area) of applicants lamp over Hanovia lamp 10. Surface area of Hanovia 88A-45 lamp 280 cm. Surface area of applicants (FIG. 5) lamp 1620 cm.

Therefore, total output of applicants lamp is: a

At power loading of 6 kw., with the lamp of FIGURE 5, the yield of 2537 A. radiation is:

lamp output lamp input At lower power loading (e.g., an input of 780 w. with straight lamp of FIGURE 1, having 520 cm. surface area) and at measured increased-brilliance factor of 5.15, the total output of applicants lamp is:

Therefore, the yield of 2537 A. radiation in this case is:

The lamp of FIGURE 5 was operated for 132 hours submersed in a 9-gal. cylindrical reaction vessel to produce pound-s of a high temperature fluorocarbon material.

FIGURE 7 shows a lamp unit, of the type shown in FIGURE 5, operatively connected in a combination suitable for continuous commercial operation. The FIG- URE 7 combination is generally comparable to that partially disclosed in FIGURE 1 using the type lamp shown in FIGURE 5, but with a more comprehensive showing of the total combination or system in which the lamp is utilized. The improved lamp of FIGURE 5 is shown submerged in the material M to be treated in reactor vessel R. The inert gas source or tank GC is provided with a pressure regulator device PR and supplies gas to the electron-impact excitable medium or metallic vapor saturator device 17 through gas dryer unit GD and variable leak device VL. Saturator device 17 causes the medium or metallic vapor to saturate the inert gas. Temperature control of the saturator device is achieved by circulator pump P 1 supplying heat exchange fluid to a. jacket in cooperation with the saturator device. This heat exchange fluid is supplied from a reservoir 160' in which the proper temperature is maintained by heater unit HR.

The inert gas carrying the medium or metallic vapor is drawn in sequence through end closure member 26, the annular zone between the outer tube 2 and inner tubes 11 and 11, the end closure member 26', shut off valve V, and liquid nitrogen-filled cold trap CT by vacuum pump VP. The pressure in this circuit is maintained at the desired low value by conventional adjustment of the components. An electrical heating conduit HT for the prevention of mercury condensation and pressure gauge G are provided to assist in the necessary control of the inert gas and the electron-impact excitable medium.

Circulator pump P2 is also supplied from reservoir 160 and circulates iheat exchange fluid as indicated in FIGURE 7 through the end closure members 26' and 26 in sequence to maintain them at the desired temperature by thermostatic means (not shown).

Circulator pump P3 is supplied with heat exchange fluid from reservoir 170 and circulates this fluid as shown in FIGURE 7 to the inner tubular elements 11 in a parallel flow arrangement to maintain the annular zone of arc discharge at the desired temperature. Reservoir 170 is provided with heater HR as well as a cooling means CW to maintain it at the desired temperature by thermostatic means (not shown).

Electrical power is supplied as discussed in the preceding discussion to the electrode assemblies through leads 9.

In submersed operation of the lamp unit combination of FIGURE 7, vacuum pump VP is first switched on and cold trap CT filled with liquid nitrogen. Variablel'eak device VL is kept closed while the unit is being pumped down. Water heater HR and circulating pumps P P P are then switched on. If desired, preheated heat exchange fluid can be supplied reservoirs 160 and 170 to shorten the over-all start-up time. Heating mantle 17 is switched on under the mercury saturator as well as heating tape HT. When the mercury begins to boil, variable-leak device VL is opened and the flow of inert gas adjusted to maintain the desired gas pressure. After a period of 5-10 minutes, electric heaters 5 are switched on, followed by the high-voltage supply. Steady-state lamp operation is normally obtained in 30 minutes.

It is believed that the operation of the improved lamp system embodying principles of this invention is cleaf from the foregoing discussions and descriptions.

In addition it is apparent that applicant has provided a novel and improved lamp unit in accordance with the objects of the invention.

Although certain specific embodiments have been described, many modifications within the spirit of the invention will occur to those skilled in the art, and all such are considered to fall within the scope of the following claims.

What is claimed is:

1. An improved high efficiency electrical arc discharge lamp unit for generating light, said unit comprising in combination; a gas-tight housing means constructed and arranged for cooperation and operative association with a photochemical reaction vessel, said housing means comprising a first elongated tubular envelope member formed of a material pervious to light generated by said unit, said housing means further comprising a first end closure member cooperating with one end of said tubular envelope member and a second end closure member cooperating with said other end of said tubular envelope member, said unit further comprising a second inner elongated tubular member cooperating with said first tubular member to define an elongated tubular zone, said unit further comprising support means in said housing means cooperating with said second tubular member to support said second tubular member inside said first tubular member and maintain said tubular zone in a configuration having a substantially uniform predetermined thickness, said unit further comprising a first electrode assembly mounted on one of said end closure members and positioned in said housing means at one end of said zone and a second electrode assembly mounted on the other of said end closure members and positioned in said housing means at the other end of said zone, said electrode assemblies adapted to be operatively connected to an electrical power supply circuit of predetermined characteristics, said unit further comprising a third means cooperating with one of said closure members for maintaining a predetermined low absolute pressure in said zone in said housing means, said unit further comprising a fourth means cooperating with one of said closure members for supplying during operation a predetermined amount of an electron-impact excitable medium carried in an inert gas to said zone in said housing means, and a fifth means cooperating with said inner tubular member to maintain a predetermined temperature in said inner tubular member and said zone, said predetermined characteristics of said power supply circuit, said predetermined thickness of said tubular zone, said predetermined pressure, said predetermined temperature, and said predetermined amount of said medium being such that upon energization of said electrode assemblies by such power supply circuit, a high intensity light-radiating arc discharge is created and maintained in said zone between said electrode assemblies to produce sufllcient light of a predetermined wave length range and intensity in said zone for transmission through said first tubular envelope member to space surrounding said unit such that significant photochemical effects can be effectively produced in the surrounding space.

2. The improved lamp unit of claim 1 in which said predetermined thickness of said zone is about equal to the eifective mean free path of the light quanta generated in the zone in order that the light generated is transmitted from the housing means without substantial reabsorption.

I 3. The improved lamp unit of claim 2 in which at least the outer surface of said inner tubular member is formed of a material having a high reflection coefficient for the light produced.

4. The improved lamp unit of claim 3 in which at least the outer surface of said inner tubular member is formed of a metallic material having a work function smaller than the energy of the radiation produced.

5. The improved lamp unit of claim 4 in which said end closure members are formed of metal and maintained at the same electrical potential as the corresponding electrode assemblies in .order to decrease channeling in the said zone during the arc discharge.

6. The improved lamp unit of claim 5 in which said first tubular envelope member is formed of quartz, said medium is mercury vapor, said electrode assemblies are formed from tungsten, and said inert gas is a gas selected from the group consisting of argon and helium.

7. The improved lamp unit of claim 6 in which said predetermined thickness is between about 1.5 and about 7 millimeters.

8. The improved lamp unit of claim 1 in which fur ther means for supplying comprises a sixth means co operating with said housing means for collecting and removing a portion of said inert gas and said metallic vapor from said zone to maintain a degree of flow of said vapor and gas through said zone during operation of said unit.

No references cited.

JAMES W. LAWRENCE, Primary Examiner.

S. D. SCHLOSSER, Assistant Examiner. 

1. AN IMPROVED HIGH EFFICIENCY ELECTRICAL ARC DISCHARGE LAMP UNIT FOR GENERATING LIGHT, SAID UNIT COMPRISING IN COMBINATION; A GAS-TIGHT HOUSING MEANS CONSTRUCTED AND ARRANGED FOR COOPERATION AND OPERATIVE ASSOCIATION WITH A PHOTOCHEMICAL REACTION VESSEL, SAID HOUSING MEANS COMPRISING A FIRST ELONGATED TUBULAR ENVELOPEE MEMBER FORMWED OF A MATERIAL PREVIOUS TO LIGHT GENERATED BY SAID UNIT, SAID HOUSING MEANS FURTHER COMPRISING A FIRST END CLOSURE MEMBER COOPERATING WITH ONE END OF SAID TUBULAR ENVELOPE MEMBER AND A SECOND END CLOSURE MEMBER COOPERATING WITH SAID OTHER END OF SAID TUBYLAR ENVELOPE MEMBER, SAID UNIT FURTHER COMPRISING A SECOND INNER ELONGATED TUBULAR MEMBER COOPERATING WITH SAID FIRST TUBULAR MEMBER TO DEFINE AN ELONGATED TUBULAR ZONE, SAID UNIT FURTHER COMPRISING SUPPORT MEANS IN SAID HOUSING MEANS COOPERATING WITH SAID SECOND TUBULAR MEMBER TO SUPPORT SAID SECOND TUBULAR MEMBER INSIDE SAID FIRST TUBULAR MEMBER AND MAINTAIN SAID TUBYLAR ZONE IN A CONFIGURATION HAVING A SUBSTANTIALLY UNIFORM PREDETERMINED THICKNESS, SAID UNIT FURTHER COMPRISING A FIRST ELECTRODE ASSEMBLY MOUNTED ON ONE OF SAID END CLOSURE MEMBERS AND POSITIONED IN SID HOUSING MEANS AT ONE END OF SAID ZONE AND A SECOND ELECTRODE ASSEMBLY MOUNTED ON THE OTHER OF SAID END CLOSURE MEMBERS AND POSITIONED IN SAID HOUSING MEANS AT THE OTHER END OF SAID ZONE, SAID ELECTRODE ASSEMBLIES ADAPED TO BE OPERATIVELY CONNECTED TO AN ELECTRICAL POWER SUPPLY CIRCUIT OF PREDETERMINED CHARACTERISTICS, SAID UNIT FURTHER COMPRISING A THIRD MEANS COOPERATING WITH ONE OF SAID CLOSURE MEMBERS FOR MAINTAINING A PREDETERMINED LOW ABSOLUTE PRESSURE IN SAID ZONE IN SAID HOUSING MEANS, SAID UNIT FURTHER COMPRISING A FOURTH MEANS COOPERATING WITH ONE OF SAID CLOSURE MEMBERS FOR SUPPLYING DURING OPERATION A PRE-DETERMINED AMOUNT OF AN ELECTRON-IMPACT EXCITABLEE MEDIUM CARRIED IN AN INERT GAS TO SAID ZONE IN SAID HOUSING MEANS, AND A FIFTH MEANS COOPERATING WITH SAID INNER TUBULAR MEMBER TO MAINTAIN A PREDETERMINED TEMPERATURE IN SAID INNER TUBULAR MEMBER AND SAID ZONE, SAID PREDETERMINED CHARACTERISTICS OF SAID POWER SUPPLY CIRCUIT, SAID PREDETERMINED THICKNESS OF SAID TUBULAR ZONE, SAID PREDETERMINED PRESSURE, SAID PREDETERMINED TEMPERATURE, AND SAID PREDETERMINED AMOUNT OF SAID MEDIUM BEING SUCH THAT UPON ENERGIZATION OF SAID ELECTRODE ASSEMBLIES BY SUCH POWER SUPPLY CIRCUIT, A HIGH INTENSITY LIGHT-RADIATING ARC DISCHARGE IS CREATED AND MAINTAINED IN SAID ZONE BETWEEN SAID ELECTRODE ASSEMBLIES TO PRODUCE SUFFICIENT LIGHT OF A PREDETERMINED WAVE LENGTH RANGE AND INTENSITY IN SAID ZONE FOR TRANSMISSION THROUGH SAID FIRST TUBULAR ENVELOPE MEMBER TO SPACE SURROUNDING SAID UNIT SUCH THAT SIGNIFICANT PHOTOCHEMICAL EFFECTS CAN BE EFFECTIVELY PRODUCED IN THE SURROUNDING SPACE. 